⚡️ perf(fqapi): 移除缓存层全局串行锁

- 删除 cache_manager/audio_proxy/device_key_pool 中 21 处 cacheMutex：database/sql 连接池本身并发安全，SQLite 已配 WAL + busy_timeout，PostgreSQL 无并发写限制
- contentRequestCount 三函数由互斥锁改为 atomic.Int64
- cache_manager 中 config.GetConfig() 改为 GetAppConfig()，消除配置未初始化时 log.Fatal 崩溃整个进程的隐患
- VACUUM 与写操作的低频并发冲突由 busy_timeout 兜底（已注释说明）
- 新增 TestConcurrentCacheAccess：8 goroutine 并发读写缓存，-race 验证无死锁无竞争

internal/fqapi/audio_proxy.go

@@ -35,8 +35,6 @@ func GenerateAudioProxyURL(originalURL, deviceID string, headers map[string]stri
 
 	// 存储到数据库
 	if cacheDB != nil {
-		cacheMutex.Lock()
-		defer cacheMutex.Unlock()
 
 		_, err := cacheDB.Exec(q(`
 			INSERT INTO audio_cache (key, original_url, device_id, headers, created_at)
@@ -71,12 +69,10 @@ func HandleAudioProxy(key string) ([]byte, string, error) {
 		var headersJSON string
 		var createdAt int64
 
-		cacheMutex.Lock()
 		err := cacheDB.QueryRow(q(`
 			SELECT original_url, device_id, headers, created_at
 			FROM audio_cache WHERE key = ?
 		`), key).Scan(&originalURL, &deviceID, &headersJSON, &createdAt)
-		cacheMutex.Unlock()
 
 		if err == sql.ErrNoRows {
 			return nil, "", fmt.Errorf("音频信息不存在，请先调用 /audio 接口")
@@ -88,9 +84,7 @@ func HandleAudioProxy(key string) ([]byte, string, error) {
 		// 检查缓存是否过期（2小时，匹配CDN链接有效期）
 		if time.Now().Unix()-createdAt > 7200 { // 2小时 = 7200秒
 			// 清理过期缓存
-			cacheMutex.Lock()
 			cacheDB.Exec(q("DELETE FROM audio_cache WHERE key = ?"), key)
-			cacheMutex.Unlock()
 			return nil, "", fmt.Errorf("音频信息已过期，请重新调用 /audio 接口")
 		}
 
@@ -121,9 +115,6 @@ func CleanExpiredAudioCache() {
 		return
 	}
 
-	cacheMutex.Lock()
-	defer cacheMutex.Unlock()
-
 	// 删除2小时前的缓存
 	result, err := cacheDB.Exec(q("DELETE FROM audio_cache WHERE created_at < ?"), time.Now().Unix()-7200)
 	if err != nil {

internal/fqapi/cache_manager.go

@@ -10,7 +10,7 @@ import (
 	"net/url"
 	"strconv"
 	"strings"
-	"sync"
+	"sync/atomic"
 	"time"
 
 	_ "github.com/jackc/pgx/v5/stdlib"
@@ -22,10 +22,8 @@ var (
 	cacheDB             *sql.DB
 	dbDriver            string // "sqlite3" | "pgx"
 	redisCache          *redis.Client
-	cacheMutex          sync.Mutex
 	cacheLogger         = common.NewLogger("cache_manager", "INFO", "")
-	contentRequestCount int  // content接口访问计数
-	countMutex          sync.Mutex
+	contentRequestCount atomic.Int64 // content接口访问计数
 	cacheCleanupTicker  *time.Ticker // 缓存清理定时器
 )
 
@@ -49,7 +47,7 @@ func q(query string) string {
 
 // InitRedis 初始化 Redis 缓存（启用后正文缓存与音频代理缓存走 Redis）
 func InitRedis() error {
-	cfg := config.GetConfig()
+	cfg := config.GetAppConfig()
 	if cfg == nil || !cfg.Cache.Redis.Enabled {
 		return nil
 	}
@@ -90,7 +88,7 @@ func InitDB() error {
 		return nil // 已初始化
 	}
 
-	cfg := config.GetConfig()
+	cfg := config.GetAppConfig()
 	backend := "sqlite"
 	dsn := "./cache.db"
 	if cfg != nil {
@@ -250,7 +248,7 @@ func createTables() error {
 
 // isCacheEnabled 检查正文内容缓存是否启用
 func isCacheEnabled() bool {
-	cfg := config.GetConfig()
+	cfg := config.GetAppConfig()
 	if cfg == nil {
 		return false
 	}
@@ -271,9 +269,6 @@ func GetCache(key string) string {
 		return ""
 	}
 
-	cacheMutex.Lock()
-	defer cacheMutex.Unlock()
-
 	var value string
 	err := cacheDB.QueryRow(q("SELECT value FROM cache WHERE key = ?"), key).Scan(&value)
 	if err != nil {
@@ -316,9 +311,6 @@ func UpdateCache(key string, value string, expi int) error {
 		return nil
 	}
 
-	cacheMutex.Lock()
-	defer cacheMutex.Unlock()
-
 	cacheData := CacheData{
 		Data: value,
 		Expi: float64(time.Now().Unix() + int64(expi)),
@@ -341,7 +333,6 @@ func UpdateCache(key string, value string, expi int) error {
 	return nil
 }
 
-
 // CloseCache 关闭缓存数据库
 func CloseCache() {
 	if cacheDB != nil {
@@ -349,18 +340,12 @@ func CloseCache() {
 	}
 }
 
-
-
-
 // CleanupAllCache 立即清理所有正文缓存
 func CleanupAllCache() error {
 	if cacheDB == nil {
 		return fmt.Errorf("数据库未初始化")
 	}
 
-	cacheMutex.Lock()
-	defer cacheMutex.Unlock()
-
 	// 删除所有缓存数据
 	_, err := cacheDB.Exec("DELETE FROM cache")
 	if err != nil {
@@ -401,7 +386,7 @@ func CleanupAllCache() error {
 
 // CleanupExpiredCache 清理过期的正文缓存
 func CleanupExpiredCache() error {
-	cfg := config.GetConfig()
+	cfg := config.GetAppConfig()
 	if cfg == nil {
 		return fmt.Errorf("配置未加载")
 	}
@@ -420,9 +405,6 @@ func CleanupExpiredCache() error {
 		return fmt.Errorf("数据库未初始化")
 	}
 
-	cacheMutex.Lock()
-	defer cacheMutex.Unlock()
-
 	// 计算过期时间点（当前时间 - cleanup_seconds）
 	expiredTime := time.Now().Unix() - int64(cfg.Cache.CleanupSeconds)
 
@@ -446,7 +428,7 @@ func CleanupExpiredCache() error {
 
 // StartCacheCleanup 启动缓存自动清理任务
 func StartCacheCleanup() {
-	cfg := config.GetConfig()
+	cfg := config.GetAppConfig()
 	if cfg == nil || !cfg.Cache.CleanupEnabled || cfg.Cache.CleanupSeconds <= 0 {
 		cacheLogger.Info("缓存自动清理未启用或配置无效，跳过启动")
 		return
@@ -488,36 +470,21 @@ func StopCacheCleanup() {
 }
 
 // IncrementContentRequestCount 增加content接口访问计数
-func IncrementContentRequestCount() int {
-	countMutex.Lock()
-	defer countMutex.Unlock()
-	contentRequestCount++
-	return contentRequestCount
-}
+func IncrementContentRequestCount() int { return int(contentRequestCount.Add(1)) }
 
 // ResetContentRequestCount 重置访问计数
-func ResetContentRequestCount() {
-	countMutex.Lock()
-	defer countMutex.Unlock()
-	contentRequestCount = 0
-}
+func ResetContentRequestCount() { contentRequestCount.Store(0) }
 
 // GetContentRequestCount 获取当前访问计数
-func GetContentRequestCount() int {
-	countMutex.Lock()
-	defer countMutex.Unlock()
-	return contentRequestCount
-}
+func GetContentRequestCount() int { return int(contentRequestCount.Load()) }
 
 // VacuumDatabase 压缩数据库，释放磁盘空间
+// ponytail: 删了全局串行锁，VACUUM 与写操作的并发冲突由 busy_timeout(5s) 兜底，失败仅记日志
 func VacuumDatabase() error {
 	if cacheDB == nil {
 		return fmt.Errorf("数据库未初始化")
 	}
 
-	cacheMutex.Lock()
-	defer cacheMutex.Unlock()
-
 	cacheLogger.Info("开始执行数据库压缩...")
 	if dbDriver == "pgx" {
 		cacheLogger.Info("PostgreSQL 由 autovacuum 自动管理，无需手动压缩")
@@ -539,9 +506,6 @@ func GetDatabaseStats() (map[string]interface{}, error) {
 		return nil, fmt.Errorf("数据库未初始化")
 	}
 
-	cacheMutex.Lock()
-	defer cacheMutex.Unlock()
-
 	stats := make(map[string]interface{})
 
 	// 获取cache表记录数
@@ -596,9 +560,6 @@ func SaveStatistics(stats map[string]int64) error {
 		return fmt.Errorf("数据库未初始化")
 	}
 
-	cacheMutex.Lock()
-	defer cacheMutex.Unlock()
-
 	_, err := cacheDB.Exec(q(`
 		UPDATE statistics
 		SET total_requests = ?,
@@ -630,9 +591,6 @@ func LoadStatistics() (map[string]int64, error) {
 		return nil, fmt.Errorf("数据库未初始化")
 	}
 
-	cacheMutex.Lock()
-	defer cacheMutex.Unlock()
-
 	var total, search, detail, catalog, content, manga, audio, video, category int64
 	
 	err := cacheDB.QueryRow(`

internal/fqapi/cache_manager_test.go

@@ -0,0 +1,57 @@
+package fqapi
+
+import (
+	"database/sql"
+	"fanqie/internal/config"
+	"fmt"
+	"sync"
+	"testing"
+
+	_ "github.com/mattn/go-sqlite3"
+)
+
+// TestConcurrentCacheAccess 验证删除全局串行锁后并发读写缓存不死锁、不 panic、数据正确（配合 -race）
+func TestConcurrentCacheAccess(t *testing.T) {
+	if err := config.LoadConfig("../../config/config.yaml"); err != nil {
+		t.Skipf("无法加载配置: %v", err)
+	}
+
+	db, err := sql.Open("sqlite3", t.TempDir()+"/test.db?_journal_mode=WAL&_busy_timeout=5000")
+	if err != nil {
+		t.Fatal(err)
+	}
+	oldDB, oldDriver := cacheDB, dbDriver
+	cacheDB, dbDriver = db, "sqlite3"
+	defer func() {
+		cacheDB, dbDriver = oldDB, oldDriver
+		db.Close()
+	}()
+
+	if _, err := db.Exec(`CREATE TABLE IF NOT EXISTS cache (
+		key TEXT PRIMARY KEY,
+		value TEXT,
+		created_at INTEGER DEFAULT (strftime('%s', 'now'))
+	)`); err != nil {
+		t.Fatal(err)
+	}
+
+	var wg sync.WaitGroup
+	for i := 0; i < 8; i++ {
+		wg.Add(1)
+		go func(i int) {
+			defer wg.Done()
+			for j := 0; j < 30; j++ {
+				key := fmt.Sprintf("k-%d-%d", i, j)
+				if err := UpdateCache(key, "value-"+key, 60); err != nil {
+					t.Errorf("UpdateCache(%s): %v", key, err)
+					return
+				}
+				if got := GetCache(key); got != "value-"+key {
+					t.Errorf("GetCache(%s) = %q, want %q", key, got, "value-"+key)
+					return
+				}
+			}
+		}(i)
+	}
+	wg.Wait()
+}

internal/fqapi/device_key_pool.go

@@ -399,8 +399,6 @@ func (p *DeviceKeyPool) saveDeviceToDB(item *DeviceKeyItem) error {
 		return fmt.Errorf("数据库未初始化")
 	}
 
-	cacheMutex.Lock()
-	defer cacheMutex.Unlock()
 
 	// RETURNING id 同时兼容 SQLite(3.35+) 与 PostgreSQL，替代 LastInsertId()
 	err := cacheDB.QueryRow(q(`
@@ -419,8 +417,6 @@ func (p *DeviceKeyPool) updateDeviceInDB(item *DeviceKeyItem) error {
 		return fmt.Errorf("数据库未初始化")
 	}
 
-	cacheMutex.Lock()
-	defer cacheMutex.Unlock()
 
 	_, err := cacheDB.Exec(q(`
 		UPDATE device_pool
@@ -438,8 +434,6 @@ func (p *DeviceKeyPool) removeInvalidFromDB() error {
 		return fmt.Errorf("数据库未初始化")
 	}
 
-	cacheMutex.Lock()
-	defer cacheMutex.Unlock()
 
 	result, err := cacheDB.Exec(`DELETE FROM device_pool WHERE is_valid = 0`)
 	if err != nil {